Project Summary - Project 4 Project 4 is a new project that addresses the epidemic of thyroid cancer. Well-differentiated thyroid cancer is increasing at an alarming rate. There has been a 3-fold increase in incidence of thyroid cancer in the past 3 decades. However, the mortality for these patients has remained very low (estimated to be ~2%). Therefore, performing a thyroidectomy for all patients with that thyroid cancer may not be necessary. This project addresses two major issues relevant to the thyroid cancer detection and management. Firstly, we will use next generation sequencing to develop and validate a molecular test that can more accurately distinguish between thyroid cancer and benign nodules in patients with needle biopsy results that are indeterminate. This molecular test analyses the expression and/or mutation of 62 individual genes and builds on our previous experience using a smaller panel of genes to diagnose thyroid cancer. In the second Aim, we will evaluate the ability of our molecular testing to differentiate low-risk thyroid cancers from more aggressive (high-risk) thyroid cancers. In order to accomplish this goal, we will first interrogate tissue samples obtained from patients who have undergone surgery for thyroid cancer, and then experience disease recurrence or distant metastases. Simultaneously, we will initiate a clinical trial to observe patients with small thyroid cancers. Patients with small cancers will undergo upfront molecular testing and then will be observed. A molecular profile of high-risk disease will be determined by the tumors from patients who progress during the observation period. This information will then be used to inform the second phase of the trial, which will use the molecular signature to separate patients into high-risk and low-risk disease for surgery or observation, respectively. Aim 1: To test the hypothesis that the NGS-based panel of mutational markers can reliably diagnose cancer in thyroid nodules. This Aim seeks to develop and validate a novel molecular analytic test that can accurately predict which thyroid nodules are malignant versus benign. We will develop the molecular test at the University of Pittsburgh and then validate the utility of this test in 8 other academic centers. Aim 2: To test the hypothesis that high-risk and low-risk differentiated thyroid cancers have distinct mutational profiles that can be detected in FNA samples and utilized to guide patient management. This Aim consists of two parts, the first sub-aim seeks to use molecular testing to characterize tissues derived from patients with aggressive disease (experience recurrence of cancer or develop metastases). The second sub- aim extends these data to develop and implement a prospective clinical trial that provides patients with small cancers to have observation instead of surgery. The data from this trial will validate that molecular testing can be used to stratify thyroid cancers into a low-risk subtype.